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U.S. Lung Cancer Rates Falling Overall, Study Finds

Yet certain types of lung malignancies are still on the rise

WebMD News from HealthDay

By Steven Reinberg

HealthDay Reporter

MONDAY, Aug. 11, 2014 (HealthDay News) -- Overall lung cancer rates are dropping, according to a new analysis of nearly a half million Americans with lung cancer. But, the news wasn't all good -- the study also found that the rates of certain types of lung cancer are increasing, according to researchers from the U.S. National Cancer Institute (NCI).

Over nearly three decades, the overall lung cancer rate has dropped approximately 12 percent, said the study's lead author Denise Riedel Lewis, an epidemiologist at the NCI.

"The good news is that lung cancer rates are declining. However, it's not as clear for certain subtypes, and we are not exactly sure of the reasons behind these increases," Riedel Lewis said.

Riedel Lewis said that while she cannot draw a definitive conclusion about what's causing the decline in lung cancer rates, she can infer that it's mostly due to decreases in smoking.

Since 90 to 95 percent of lung cancers in the United States are caused by smoking, these changes in lung cancer rates likely reflect that fewer people are smoking, she said.

One type of lung cancer that's on the rise is called adenocarcinoma, Riedel Lewis said. Adenocarcinomas account for about 40 percent of all lung cancers, according to the American Cancer Society (ACS). They usually start in the outer part of the lungs. They tend to grow slower than other types of lung cancer and are more likely to be found before spreading outside the lung.

Dr. Norman Edelman, a senior medical advisor to the American Lung Association, said this type of cancer may be increasing as a result of changes in the way smokers smoke.

"The deeper you breathe in smoke, the more likely the cancer-causing tars are going to get into the outer area of the lungs, and that's where adenocarcinoma starts," he said.

The increase in adenocarcinoma may be due to people smoking low-tar, low-nicotine -- so-called light -- cigarettes, Edelman said. "People were inhaling more deeply and smoking more just to get the amount of nicotine they were looking for," he said.